//图片按比例缩放
var flag = false;
function DrawImage(ImgD, iwidth, iheight) {
	// 参数(图片,允许的宽度,允许的高度)
	var image = new Image();
	iwidth = 200;
	iheight = 200;
	image.src = ImgD.src;
	
	if (image.width > 0 && image.height > 0) {
		flag = true;
		if (image.width / image.height >= iwidth / iheight) {
			if (image.width > iwidth) {
				ImgD.width = iwidth;
				ImgD.height = (image.height * iwidth) / image.width;
			} else {
				ImgD.width = image.width;
				ImgD.height = image.height;
			}
			ImgD.alt = image.width + "×" + image.height;
		} else {
			if (image.height > iheight) {
				ImgD.height = iheight;
				ImgD.width = (image.width * iheight) / image.height;
			} else {
				ImgD.width = image.width;
				ImgD.height = image.height;
			}
			ImgD.alt = image.width + "×" + image.height;
		}
	}
}